X PREFACE. 



lations among the twenty-one coefficients, which virtually re- 

 duce the medium to one symmetrical with respect to three 

 planes at right angles to one another. 



This paper, read May 20, 1839, was his last production. 

 Another, "On the Vibrations of Pendulums in Fluid Media," 

 read before the Royal Society of Edinburgh, on Dec. 16, 1833, 

 will be found at the end of this collection. The problem here 

 considered is that of the motion of an inelastic fluid agitated 

 by the small vibrations of a solid ellipsoid, moving parallel to 

 itself. 



I have to express my thanks to the Council of the Cam- 

 bridge Philosophical Society, and to that of the Royal Society 

 of Edinburgh, for the permission to reproduce the papers pub- 

 lished in their respective Transactions which they have kindly 

 given. 



N. M. FERRERS. 



GONVILLE AND CAIUS COLLEGE, 



Dec. 1870. 



